J Plant Ecol ›› 2017, Vol. 10 ›› Issue (4): 670-680.

• Research Articles •

### Effects of soil warming history on the performances of congeneric temperate and boreal herbaceous plant species and their associations with soil biota

Madhav P. Thakur1,2,*, Peter B. Reich3,4, Cameron Wagg5, Nicholas A. Fisichelli6, Marcel Ciobanu7, Sarah E. Hobbie8, Roy L. Rich3, Artur Stefanski3 and Nico Eisenhauer1,2

1. 1 German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Mitte, Deutscher Platz 5E, 04103 Leipzig, Germany; 2 Institute of Biology, Leipzig University, Johannisallee 21, 04103 Leipzig, Germany; 3 Department of Forest Resources, University of Minnesota, 1530 North Cleveland Avenue, St. Paul, MN 55108, USA; 4 Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, New South Wales 2751, Australia; 5 Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; 6 Forest Ecology Program, Schoodic Institute at Acadia National Park, Winter Harbor, ME 04693, USA; 7 Institute of Biological Research, Branch of the National Institute of Research and Development for Biological Sciences, 48 Republicii Street, 400015 Cluj-Napoca, Romania; 8 Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA
• Received:2016-01-22 Accepted:2016-06-19 Published:2017-07-24
• Contact: Thakur, Madhav

Abstract: Aims Climate warming raises the probability of range expansions of warm-adapted temperate species into areas currently dominated by cold-adapted boreal species. Warming-induced plant range expansions could partly depend on how warming modifies relationships with soil biota that promote plant growth, such as by mineralizing nutrients. Here, we grew two pairs of congeneric herbaceous plants species together in soil with a 5-year warming history (ambient, +1.7°C, +3.4°C) and related their performances to plant-beneficial soil biota.
Methods Each plant pair belonged to either the mid-latitude temperate climate or the higher latitude southern boreal climate. Warmed soils were extracted from a chamberless heating experiment at two field sites in the temperate-boreal ecotone of North America. To isolate potential effects of different soil warming histories, air temperature for the greenhouse experiment was identical across soils. We hypothesized that soil with a 5-year warming history in the field would enhance the performance of temperate plant species more than boreal plant species and expected improved plant performances to have positive associations with plant growth-promoting soil biota (microbial-feeding nematodes and arbuscular mycorrhizal fungi).
Important findings Our main hypothesis was partly confirmed as only one temperate species performed better in soil with warming history than in soil with history of ambient temperature. Further, this effect was restricted to the site with higher soil water content in the growing season of the sampling year (prior to soil collection). One of the boreal species performed consistently worse in previously warmed soil, whereas the other species showed neutral responses to soil warming history. We found a positive correlation between the density of microbial-feeding nematodes and the performance of one of the temperate species in previously wetter soils, but this correlation was negative at the site with previously drier soil. We found no significant correlations between the performance of the other temperate species as well as the two boreal species and any of the studied soil biota. Our results indicate that soil warming can modify the relation between certain plant species and microbial-feeding nematodes in given soil edaphic conditions, which might be important for plant performance in the temperate-boreal ecotone.

Aims Climate warming raises the probability of range expansions of warm-adapted temperate species into areas currently dominated by cold-adapted boreal species. Warming-induced plant range expansions could partly depend on how warming modifies relationships with soil biota that promote plant growth, such as by mineralizing nutrients. Here, we grew two pairs of congeneric herbaceous plants species together in soil with a 5-year warming history (ambient, +1.7°C, +3.4°C) and related their performances to plant-beneficial soil biota.
Methods Each plant pair belonged to either the mid-latitude temperate climate or the higher latitude southern boreal climate. Warmed soils were extracted from a chamberless heating experiment at two field sites in the temperate-boreal ecotone of North America. To isolate potential effects of different soil warming histories, air temperature for the greenhouse experiment was identical across soils. We hypothesized that soil with a 5-year warming history in the field would enhance the performance of temperate plant species more than boreal plant species and expected improved plant performances to have positive associations with plant growth-promoting soil biota (microbial-feeding nematodes and arbuscular mycorrhizal fungi).
Important findings Our main hypothesis was partly confirmed as only one temperate species performed better in soil with warming history than in soil with history of ambient temperature. Further, this effect was restricted to the site with higher soil water content in the growing season of the sampling year (prior to soil collection). One of the boreal species performed consistently worse in previously warmed soil, whereas the other species showed neutral responses to soil warming history. We found a positive correlation between the density of microbial-feeding nematodes and the performance of one of the temperate species in previously wetter soils, but this correlation was negative at the site with previously drier soil. We found no significant correlations between the performance of the other temperate species as well as the two boreal species and any of the studied soil biota. Our results indicate that soil warming can modify the relation between certain plant species and microbial-feeding nematodes in given soil edaphic conditions, which might be important for plant performance in the temperate-boreal ecotone.